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October 11, 2024 - Ephemeral Lakes Dot the Sahara Desert
October 9, 2024
September 10, 2024
August 14, 2024
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Everyone knows that, in general, the Sahara Desert is a hot, dry, barren expanse that sweeps across much of Northern Africa. Most of the region receives less than 3 inches (76 millimeters) of rain a year, although the rainfall can be variable across the large desert. Overall, water is quite scarce across the Sahara and lakes are nearly non-existent.
However, when it rains in the world’s largest non-polar desert, it can most certainly pour.
The most recent example of this came in the form of an extratropical cyclone that pushed across the northwestern Sahara on September 7 and 8, 2024, and drenched large, treeless swaths of Morocco, Algeria, Tunisia, and Libya—areas that only rarely receive rain. On September 10, NASA’s Earth Observatory reported that preliminary satellite analysis showed accumulation of up to 200 millimeters (7.8 inches) in some areas. That’s more than what much of the region receives in an entire year.
While most of the rain fell in sparsely populated areas, several villages in Morocco faced flash floods, damaged roads, and spoiled water supplies, according to news reports. The rain also changed the landscape, at least temporarily. Several ephemeral lakes—lakes that are usually dry but can hold water under wet conditions— sprang back to life, thanks to plentiful rainfall, especially in Morocco and Algeria.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired a set of false-color images that show the appearance of several ephemeral lakes before the rains (April 14, 2024) after the deluge (September 10, 2024), as well as the shrinkage of the lakes over several weeks of sweltering and dry heat that is more typical desert weather (October 9, 2024). In this type of image, water looks blue—shallow water is light blue and deeper water looks darker. Vegetation shows up as bright green and open land, sand, and rocky outcrops are seen in tones of tan and brown.
Each Terra MODIS image can be viewed by clicking on the corresponding date under the images. In the top image, acquired October 9, several small lakes dot the dry desert landscape across part of Morocco (west) and Algeria (east). Also, in the southeast (lower right) section of the image, one small lake is surrounded by a thin layer of water (light blue). On September 10, a few days after the flooding rains, the lakes are larger and shallow water sprawls across channels and ephemeral lakebeds. The April 14 image shows a much more typical scene across the region – a sweeping view of sand dunes and rocky outcroppings with a little vegetation on the slopes of the Atlas Mountains—with no lakes in sight.
Image Facts
Satellite:
Terra
Date Acquired: 10/9/2024
Resolutions:
1km (147 KB), 500m (365 KB), 250m (827.6 KB)
Bands Used: 7,2,1
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
October 9, 2024 September 10, 2024 August 14, 2024
Everyone knows that, in general, the Sahara Desert is a hot, dry, barren expanse that sweeps across much of Northern Africa. Most of the region receives less than 3 inches (76 millimeters) of rain a year, although the rainfall can be variable across the large desert. Overall, water is quite scarce across the Sahara and lakes are nearly non-existent.
However, when it rains in the world’s largest non-polar desert, it can most certainly pour.
The most recent example of this came in the form of an extratropical cyclone that pushed across the northwestern Sahara on September 7 and 8, 2024, and drenched large, treeless swaths of Morocco, Algeria, Tunisia, and Libya—areas that only rarely receive rain. On September 10, NASA’s Earth Observatory reported that preliminary satellite analysis showed accumulation of up to 200 millimeters (7.8 inches) in some areas. That’s more than what much of the region receives in an entire year.
While most of the rain fell in sparsely populated areas, several villages in Morocco faced flash floods, damaged roads, and spoiled water supplies, according to news reports. The rain also changed the landscape, at least temporarily. Several ephemeral lakes—lakes that are usually dry but can hold water under wet conditions— sprang back to life, thanks to plentiful rainfall, especially in Morocco and Algeria.
The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired a set of false-color images that show the appearance of several ephemeral lakes before the rains (April 14, 2024) after the deluge (September 10, 2024), as well as the shrinkage of the lakes over several weeks of sweltering and dry heat that is more typical desert weather (October 9, 2024). In this type of image, water looks blue—shallow water is light blue and deeper water looks darker. Vegetation shows up as bright green and open land, sand, and rocky outcrops are seen in tones of tan and brown.
Each Terra MODIS image can be viewed by clicking on the corresponding date under the images. In the top image, acquired October 9, several small lakes dot the dry desert landscape across part of Morocco (west) and Algeria (east). Also, in the southeast (lower right) section of the image, one small lake is surrounded by a thin layer of water (light blue). On September 10, a few days after the flooding rains, the lakes are larger and shallow water sprawls across channels and ephemeral lakebeds. The April 14 image shows a much more typical scene across the region – a sweeping view of sand dunes and rocky outcroppings with a little vegetation on the slopes of the Atlas Mountains—with no lakes in sight.
Image Facts
Satellite:
Terra
Date Acquired: 10/9/2024
Resolutions:
1km (147 KB), 500m (365 KB), 250m (827.6 KB)
Bands Used: 7,2,1
Image Credit:
MODIS Land Rapid Response Team, NASA GSFC
